Waste processing apparatus and method featuring water removal

ABSTRACT

The present invention includes an apparatus and method for processing solid waste products. The invention features periodic removal of water preferably while the contents are under pressure. The apparatus comprises a rotatably mounted cylindrical vessel having a first end, a second end and an interior surface, at least one end terminating in a hatch that may be opened to allow access to the interior of the vessel and sealably closed to allow pressurization of the vessel; a steam inlet for injecting stem disposed at one or both ends; and one or more valves for exhausting water periodically as the waste mass is being processed.

TECHNICAL FIELD

The present invention relates to the treatment of municipal solid wasteand the like.

BACKGROUND OF THE INVENTION

The present invention relates to systems and methods for treatingprocess material and, more particularly, to systems and methods fortreating municipal solid waste material, medical waste material,reclaimed paper and the like.

As a result of increasing scarcity of landfills and more stringentenvironmental regulations, efforts have been made to reduce the volumeof process material, such as municipal solid waste (“MSW”) and papermaterial, such as newsprint and other reclaimed and recycled paperproducts as a step in the process of disposing of the material, eitherby depositing it in landfills, incinerating it or recycling it.

Systems and methods have been developed to break down such material fordisposal, or in the case of paper products, use as insulation.

An example of such a process and device is U.S. Pat. No. 5,190,226,which discloses an apparatus and method for separation, recovery andrecycling of MSW. The apparatus includes a rotating drum which is fed atan upstream end by a reciprocating ram, a steam source which isconnected to introduce high temperature steam into the drum, and aspiral rib or flight mounted within the drum to transport materialdeposited in an upstream end of the drum along the length of the drum.

Another example is described in U.S. Pat. No. 5,119,994 that describes asteam treatment vessel held stationary, preferably at an angle to thehorizontal.

One of the disadvantages of the arrangements of the prior art is thatportions of the waste product charge in the vessel become compacted,either passively by maintaining the vessel at a fixed position withrespect to the horizontal, or actively through the use of spiral orhelical rib arrangements that urge portions of the charge against activesurfaces in a horizontal direction (or a direction parallel to thelongitudinal axis of the vessel) as the vessel is rotated. In someinstances, the compacted portions of the waste product charge causeportions of the waste product charge to be sequestered from the steamtreatment environment.

Another disadvantage of the prior art is that prior systems and methodsdo not allow for the most advantageous control and distribution ofenergy placed into the vessel, and its efficient transfer to the wastecharge mass. In addition, each charge of waste products will vary in itsconstituents, and thereby in its heat capacity and in its energyrequirements for effective treatment. In methods of the prior art,either the process parameters (temperature, pressure, or time) had to bevaried with each charge of waste, or the consistency of the processedproduct (i.e., particle size, moisture content, degree of break down andprocessing generally) varied with batch to batch. This made aneconomically and technically viable industrial process for the treatmentof waste less than efficient.

Accordingly, it is also advantageous to be able to determine the heatcapacity of a given charge of waste products thereby to determine theenergy requirements for effective treatment of that charge, in ordertreatment can be carried out with higher efficiency.

One method of attempting to reach achieve more efficient treatment isdescribed in U.S. Pat. No. 6,397,492 and involves the continual supplyof steam during loading, while simultaneously rotating the vessel, so asto break down the waste during loading to a material of roughly uniformdensity, so that the same mass of waste is processed in each batch.However, this process requires a separate steam treatment during loadingwhich results in greater overall time requirements for each waste batch.

Accordingly, there remains a need for methods that allow for greatertime and energy efficiency while allowing the process of waste incharges that vary in weight and constituents.

In addition, it is also desirable to be able to reduce the amount ofwater in the processed waste mass to make it amenable for furtherprocessing into fuel pellets. As excess water typically must be removedby active drying, this requires additional time and energy investment.Accordingly, another aspect of the present invention addresses the needto efficiently remove excess water, especially that in the interstitialspaces of the waste material mass.

The present invention accordingly represents an improvement over priorart apparatus and methods, such as those described in U.S. Pat. Nos.5,540,391; 5,116,363; 5,253,764; 5,190,226; 5,361,994; 5,427,650;5,407,809; and 6,397,492, and in published European Patent ApplicationNo. 02758620.5; all of which are incorporated herein by reference. Thepresent invention also represents an improvement over co-pendingapplication Ser. No. 11/122,341, which is hereby incorporated byreference.

SUMMARY OF THE INVENTION

The present invention includes an apparatus for processing solid wasteproducts, the apparatus comprising a rotatably mounted cylindricalvessel having a first end, a second end and an interior surface, atleast one end terminating in a hatch that may be opened to allow accessto the interior of the vessel and sealably closed to allowpressurization of the vessel; a steam inlet for injecting stem disposedat one or both ends; a plurality of substantially straight bladesprotruding from the interior surface of the vessel, and each the bladeextending substantially the entire length of the vessel, so as to becapable of transporting waste material from the bottom of the vesseltoward the top of the vessel while rotating, and releasing the wastematerial to fall to the bottom of the vessel; and at least one actuatorfor moving the vessel between a position wherein the first end is higherthan the second end and a position wherein the second end is higher thanthe first end (that is, such that the vessel is moved between a positionwherein the first end is directed upward from the horizontal, and aposition wherein the second end is directed upward from the horizontal).

The vessel may be supported in any fashion that allows this movement. Itis preferred that the vessel be supported by a hinged fulcrum pointabout which it may be moved.

The vessel further includes at least one door or hatch, or similar meansto access the interior of the vessel for loading and unloading the wastecharge, which may be transported to the vessel by a conveyor or othertraditional means.

The apparatus includes a means for rotating the vessel, such as thoseknown and used in the art, such as trunnion rings and rollers, orchain-driven gear and sprocket systems or a “spud” ring. Any stablemethod of rotating the vessel at a controlled speed would be suitable.The rotation of the vessel however must also be able to accommodate itsmovement by the actuator(s) as described herein.

The arrangement of the blades and the interior of the vessel preferablyare such that there are essentially no surfaces against which the chargeof waste products may become compressed laterally during rotation of thevessel; i.e., in a direction parallel to the longitudinal axis of thevessel; and that an open central region is provided throughsubstantially the entire length of the vessel (i.e., the treatment spaceof the vessel). Such an arrangement permits portions of the charge ofwaste products to be transported from the bottom of the vessel towardthe top of the vessel during rotation, and released to fall to thebottom of the vessel through the pressurized steam environment asdiscreet relatively low density portions to increase the surface area ofthat portion with respect to the steam environment of the vessel.

In an alternative embodiment, the blades may be arranged such thatadjacent pairs of blades converge toward opposite ends of the vessel. Inthis variation, it is preferred that each blade be provided with aslight twist along its length such that it provides a slight timebetween the fall of the portion of the mass on the upper end of theblade as it rises toward the top of the vessel upon rotation, withrespect to the portion of the mass on the relatively lower end of theblade. In this regard, the blades are slightly twisted such that ends ofadjacent blades that converge are twisted away from one another whileends of adjacent blades that diverge are twisted toward one another.

The vessel will have many of the same characteristics of those known andused in the art, in terms of being designed to contain large quantitiesof matter (i.e., several tons) and to hold those contents underpressure.

The steam inlet(s) is/are provided with steam by steam conduits that areadapted to accommodate movement and rotation of the vessel. The steamconduits may be any conduit material appropriate for the transmission ofhigh pressure steam. The conduits are flexible or otherwise providedwith sufficiently flexible or articulated joints to accommodate themovement and rotation of the vessel, and are typically controlled by oneor more valves for selectively introducing steam into and out of thevessel during the processing of the waste. The steam may be provided atany location along the length of the vessel, and several arrangementsare known for providing a number of steam inlets along the length ofsuch a vessel. However, the simplest arrangement is to provide steaminlets at one or both ends of the vessel. The steam provided to thevessel may be saturated steam or super-heated steam, and may be providedstatically or as a stream through the vessel, or even if the form ofdiscreet steam pulses into the vessel, such as pulses of super-heatedsteam.

The actuators may be any apparatus capable of moving the vessel betweena position wherein the first end is higher than the second end and aposition wherein the second end is higher than the first end. Theactuator typically is adapted to move the vessel between a positionwherein the first end is higher than the second end and a positionwherein the second end is higher than the first end at such a rate so asto be capable of leveling a charge of solid waste products disposedtherein. Examples may include hydraulic actuators and mechanical screwactuators, which may be provided in pairs disposed respectively oneither side of the gravitational center of the vessel. The actuators maybe for instance, linear mechanical screw actuators, such as thosecommercially available under the name Joyce ComDrive from Joyce ofDayton, Ohio, and those commercially available from Duff-Norton ofCharlotte, N.C.

The apparatus may also include load sensors independent of or associatedwith the actuator(s). The load sensors may be of any type capable ofsensing and recording loads of the magnitude typically associated withwaste treatment vessels of the type of the present invention.

The apparatus optionally includes a microprocessor or PLC controllerassociated with the load sensors, the microprocessor or PLC controllerhaving programming instructions so as to determine the load distributedwithin the vessel, such as at the position of each of the actuators. Themicroprocessor or PLC controller further may be adapted to signal theactuators in response to changes in the distribution of a charge ofwaste products contained in the vessel.

The apparatus may also include a plurality of thermocouples orthermometers disposed along the length of the vessel. These may have amicroprocessor or PLC controller associated with them, themicroprocessor or PLC controller having programming instructions adaptedto calculate the amount of energy absorbed by a charge of waste productscontained in the vessel over time.

The apparatus may also include a control system to operate the vesselsystem and may comprise a computer program code product that controls acomputer comprising one or more central processor units (CPUs)interconnected to a memory system with peripheral control components,such as for example, a Pentium® microprocessor, commercially availablefrom Intel Corporation, Santa Clara, Calif.

Most preferably the apparatus has load sensors associated with orindependent of the actuator(s), the load sensors adapted to determinethe mass of a charge of waste products contained in the vessel, and amicroprocessor or PLC controller having programming instructions so asto determine the energy absorption per mass of a charge of wasteproducts contained in the vessel.

The apparatus also includes at least one motor or other means forrotating the vessel. The motor(s) may be connected to the vessel throughappropriate drive/transmission means. For instance, the motors may beconnected to drive sleeves that surround the vessel, as shown in thefigures. Typically, the motor and drive means will be mounted in such anarrangement so as to move along with the movement of the vessel itself,such as by being mounted on a moveable frame supporting the vessel.

Apparatus with Tip-Leveling Actuator Only

Still another variation of the present invention is an apparatus forprocessing solid waste products, comprising: a rotatably mountedcylindrical vessel having a first end, a second end and an interiorsurface, at least one end terminating in a hatch that may be opened toallow access to the interior of the vessel and sealably closed to allowpressurization of the vessel; a steam inlet for injecting stem disposedat least one of the ends; a plurality of substantially straight bladesprotruding from the interior surface of the vessel, and each bladeextending substantially the entire length of the vessel (i.e., thecontained volume that provides steam treatment and movement of the wastecharge), so as to be capable of transporting waste material from thebottom of the vessel toward the top of the vessel, and releasing thewaste material to fall to the bottom of the vessel; and at least oneactuator for moving the vessel between a position wherein the first endis higher than the second end and a position wherein the second end ishigher than the first end.

Apparatus with Agitating Leveling Means Only

Yet another variation of the present invention is an apparatus forprocessing solid waste products, the apparatus comprising: a rotatablymounted cylindrical vessel having a first end, a second end and aninterior surface, at least one end terminating in a hatch that may beopened to allow access to the interior of the vessel and sealably closedto allow pressurization of the vessel; a steam inlet for injecting stemdisposed at least one of the ends; and at least one actuator foragitating the vessel so as to be capable of leveling a charge of solidwaste products disposed therein.

The apparatus of the present invention may also include one or morevalves to remove water from the vessel during processing. The water maybe evacuated to atmospheric pressure, or may even be evacuated under theinfluence of vacuum.

Method of Treating Waste Involving Free Fall Through Low Density Zone

The present invention also includes a method of processing solid wasteproducts in a vessel having a central longitudinal axis, comprising:loading the vessel with a charge of solid waste products along thebottom of the vessel, the vessel having a plurality of substantiallystraight blades extending from the interior surface of the vessel andeach blade extending substantially the entire length of the vessel;sealing the vessel; introducing steam into the vessel; rotating thevessel so as to cause the charge of solid waste products to be movedfrom the bottom of the vessel to toward the top of the vessel andallowed to fall through the vessel so as to maintain a low densityregion of waste substantially along the length of the vessel; andthereafter depressurizing the vessel and unloading the processed wastetherefrom.

Typically, the solid waste products are moved from the bottom of thevessel to toward the top of the vessel and allowed to fall in a seriesof discreet portions through a relatively low density region of theinterior of the vessel.

It is preferred that the vessel is rotated without substantialcompression of the charge of solid waste products along a directionparallel to the central longitudinal axis.

Another preferred aspect of the present method is that the solid wasteproducts are transported back and forth along a direction parallel tothe central longitudinal axis while the vessel is being rotated. Thisresults in both longitudinal agitation and active leveling of thecharge. This may be accomplished by tilting the vessel using theactuators, and/or by action of the plurality of blades when theconfiguration is used wherein the blade pairs converge toward oppositeends.

It is most preferred that the blades be provided in pairs that convergein alternating fashion toward opposite ends of the vessel to provide anadditional side-to side movement of the waste charge mass. Further, theblades may be provided with a twist about their longitudinal axis suchthat a time delay is provided between the descent of the portions of thewaste charge mass that are raised by the relatively higher portion ofeach angled blade, and the portions of the waste charge mass that areraised by the relatively lower portion of each angled blade, as thevessel rotates.

It is most preferred that the steam is introduced from both ends of thevessel, and most preferred that the steam is superheated steamintroduced in pulses into the vessel using appropriate valve andpressure release systems.

In another preferred variation of the method of the invention, the massdistribution of the charge of solid waste products is measured while thevessel is rotating, and, optionally the energy absorbed by the charge ofsolid waste products is measured while the vessel is rotating.

The method of the present invention may also feature measuring the massdistribution of the charge of solid waste products and measuring theenergy absorbed by the charge of solid waste products while the vesselis rotating, and determining the time required to treat the charge ofsolid waste products from the amount of energy absorbed by the charge ofsolid waste products over time. This determination in turn allows theoperator to conclude the treatment of the charge of solid waste productsbased on time at temperature, rather than on a fixed schedule, providinga higher quality result. This may be done by the operator orautomatically through feedback control from the microprocessors or PLCcontrollers.

The apparatus and method of the present invention offers advantages overprior systems that featured helical or augur arrangements designed tomove the charge of solid waste products from one end of the vessel tothe other, or other interior arrangements that feature surfaces disposedperpendicular to the longitudinal axis of the vessel. These arrangementsoften result in compression of portions of the waste product charge,preventing the efficient and complete treatment of those portions.

The apparatus and method of the present invention in contrast permitsthe formation of a zone that extends the length of the vessel byleveling the load prior to treatment initiation or shortly after thestart of treatment. The blades of the apparatus of the present inventiontake portions of the waste product charge and successively raise themand allow them to fall through this low density zone, withoutsubstantial compression of any portion of the waste product charge, suchas is brought about by transportation of the charge along thelongitudinal axis of the vessel, or by maintaining the vessel in atitled position with respect to the horizontal.

In addition, the apparatus and method of the present invention allowsboth the load and temperature of zones within the vessel to bemonitored.

Water Removal Method

The present invention also includes a method of control of the amount ofwater present throughout the cycle of processing solid waste products ina vessel, comprising: (1) loading the vessel with a charge of solidwaste products along the bottom of the vessel; (2) sealing the vessel;(3) introducing steam into the vessel so as to pressurize the vessel;(4) rotating the vessel so as to cause the charge of solid wasteproducts to be moved from the bottom of the vessel to toward the top ofthe vessel, whereby liquid water typically collects at the bottom of thevessel; (5) periodically removing aliquots of liquid water (as water orsteam) from the vessel, preferably while the vessel remains pressurized;and (6) thereafter depressurizing the vessel and unloading the processedsolid waste therefrom.

Under normal operating conditions, the water in the vessel normally willbe in a superheated condition such that upon being exhausted it willbecome steam. The water typically will be removed from a point at ornear the bottom of the vessel, or at least from a point below the upperboundary of the waste mass, as can be seen in FIG. 8.

There are a range of materials collectively known as lignin. Generallyaccepted ranges for the glass transition temperature of lignin focus on240-295° F. as the beginning range for wood softening. Mostthermochemical pulping is carried out in the range of 212-338° F. (lowertemperatures make longer fibers: higher temperatures remove morelignin). The use of a high temperature, such as in our range, has thedual advantage of producing short fibers (for easy separations) and lowlignin fibers (again, making post treatment separations easier whileproviding a higher quality fiber product for post-processing uses).

In the method of the present invention, it is preferred to maintain atemperature below 356° F. to retain the valuable hemicellulose in thefibers, and below about 338° F. to prevent plastics decomposition, butas high as possible for rapid and complete removal of the various lignincomponents.

In accordance with the present invention, steam is injected into thevessel to raise its temperature by the transfer of latent and sensibleheat from the steam to the vessel contents and walls, to reach effectivelevels of heat and pressure for waste processing. The vessel contents,when comprising waste stream material, are typically about 28% moisture,and warm up as steam condenses. As the steam is continuously added,eventually (in accordance with prior methods), the temperature andpressure rise to a saturated condition, typically more than 50 psia andabove about 302° F. In accordance with prior methods, after the time attemperature is realized, the pressure in the boiler is released, and thevessel and its contents equilibrate to a temperature at water boilingpoint by flashing off (evaporating) some of the water in the vessel.Prior art processes have resulted in a cooked product with higher watercontent than was found in the original MSW. More recently, systems havebeen developed that feature a vessel wherein the steam heat is added viaa closed jacket, preventing contact with the steam. This offers someadvantages for water management, but at a major complication in theexpense of the equipment and in the time necessary to raise thetemperature.

The present invention preferably uses higher temperatures (typically 300to 335° F.) and pressures (typically 70-110 psia) for the autoclavingprocess. A substantially dryer final product can be created as aconsequence of operating the vessel at a higher design temperature andpressure, combined with the drainage of free water during the vesseloperations. A relatively higher-temperature operation results in morewater evaporation during the end-of-cycle steam flash, such that theextra evaporation offsets the extra water added (as steam) to reach ahigher final temperature. As a consequence, to achieve a dryer productone would be encouraged to operate the vessel at a temperature as highas otherwise allowed (110 psia gauge/335° F.).

Additional dryness derives from the in-process water drain that isanother aspect of the present invention. One might conclude that thesensible heat used to raise vessel water to temperatures in excess ofboiling is recovered at the end of the cycle when the excess sensibleheat is converted latent heat by boiling off some of the water. Whilethat is conceptually correct, thermodynamic models show that a higherstate of product dryness occurs as a result of draining free water atthe end of the cycle, prior to depressurization. Such draining reducesthe mass of water available for evaporation during depressurization:modeling of a typical system under ideal circumstances shows that thevessel water concentration can be lowered, for instance, from itsoriginal 27% to a final 21% (even less if water in the MSW is freedduring the process).

It is estimated that the water concentration in the residual fibershould be 11-12% if condensate is first drained off.

The present invention includes the removal of water prior to steamflashing, energy savings derive from removing free water at lowertemperatures, whether continuously during the cycle or at stages withinthe cycle. In this regard, the vessel may be provided with a vacuum pump(or similar system) to be activated after the steam flash, such thateven further percentage water may be removed. The vacuum pump may alsobe applied to remove some free water during the initial pump down.

The method of the present invention may be carried out using anapparatus of the present invention. The vessel of the present inventionmay be provided with at least one valve along one side of the vessel. Inthe case of the vessel of the present invention, is preferred that thevalve is on one or both ends such that the vessel may be titled from thehorizontal to move the liquid water toward one end of the vessel formost efficient exhaustion, and from the bottom of the vessel or at leastfrom a point below the upper boundary of the waste mass. It is alsopreferred that the water may be exhausted under vacuum using airtightfittings placed on the valve(s), and drawing upon the valve(s) usingvacuum pumps (or similar systems).

The water concentration in the residual fiber should be about 50%following the high temperature steam removal: lower temperatureoperations would increase that to 55% or more. Typically, the waterconcentration in the residual fiber should be 11-12% if condensate isfirst drained off.

With one exception, prior disclosed art uniformly teaches the removal ofpressure and steam from a rotating autoclave vessel through the coaxialdrain(s) on the vessel centerline. This process provides the opportunityto remove pressurized steam and any free water present above thelocation of the valve, and such steam that may be generated as theconsequence of the release of pressure.

The sole exception in prior art is thermomechanical pulping system. InTMP, a surfeit of water is used to wash the pulp fibers, and in onepatent, an underdrain is provided to for the sole purpose of removingexcess free water prior to removal of the wet pulp.

Experience shows that the vessel contents after cooking MSW consist ofmetal products, broken glass, “dirt”, coalesced plastic products,degraded cellulose fibers, and water (containing water contaminants).When there is a screened drain at the bottom of the vessel, the dirt,metal products, and degraded cellulose fibers are present above thedrain. Free water is present below the drain, and remaining water issaturated in the interstitial spaces of the fibrous material. In MSWsystems, little, if any, free water is present above the fibrousmaterial. Above the fibrous material, the free space containshigh-pressure steam.

In the present invention, when a screened drain is opened at or near thebottom of the vessel, the region around the drain flashes into steam.The steam, as it is trapped by the overhead confining fibrous materialmat, explosively escapes toward the drain, thereby entraining anddriving additional interstitial water toward the drain.

At the same time, the high-pressure gradient on top of the fibrousmaterial and the drain acts effectively as a pressure filter, forcinginterstitial water toward the drain.

This process of pressure-entrainment-extraction of water, combined withevaporation, continues until the filter cake clogs and becomesessentially non-porous. At that time, a simple rotation of the vesselmay be carried out to break up the filter cake (and/or, the vessel istilted and a second valve is opened), and the process is repeated untilthe vessel and its residual contents have cooled (from the conversion ofsensible heat to latent heat) to below the ambient pressure boilingpoint of water.

Accordingly, another aspect of the present invention is the provision ofa high vessel pressure (typically above about 5 atmospheres) to assistin the dewatering and drying of the vessel contents. Experimentation hasshown that a residual water concentration below about 20% is achievable.The present invention thus allows for the vessel to be re-pressurizedwith air or steam to assist in the pressure-forced removal of water.

The present invention also includes a method of dewatering a processedor processing waste stream mass on the type to which the inventionrelates, such as processed or processing waste stream mass comprising asubstantial amount of cellulosic materials or other materials thatentrain water, such as interstitial water.

The method of the present invention thus includes a method of processingsolid waste products in a vessel, comprising loading the vessel with acharge of solid waste products along the bottom of the vessel; sealingthe vessel; introducing steam into the vessel so as to pressurize thevessel; rotating the vessel so as to cause the charge of solid wasteproducts to be moved from the bottom of the vessel to toward the top ofthe vessel; periodically removing aliquots of liquid water from thevessel; and thereafter depressurizing the vessel and unloading theprocessed solid waste therefrom. It is preferred that the vessel remainspressurized during the removal of aliquots of water, and that the wateris removed from a point below the mass such that aliquots of liquidwater or steam are forced from the mass vessel remains pressurizedduring the removal of aliquots of water.

It is also preferred that the water is bound in the charge of solidwaste products, and the pressure with the vessel is cycled between alower pressure by the exhaustion of steam to cause the evaporation ofthe bound water, and a higher pressure by the introduction of steam.Typically, the lower pressure is in a range of from about 5 psia toabout 15 psia.

Preferably, the vessel comprises a valve disposed on one side of thecenter axis thereof and one end of the vessel is positioned lower thanthe opposite end prior to the removal of an aliquot of liquid water fromthe vessel.

The present method also includes dewatering processed or processingsolid waste products in a vessel, by loading the vessel with a charge ofsolid waste products along the bottom of the vessel; sealing the vessel;introducing steam into the vessel so as to pressurize the vessel;processing the charge of solid waste products so as to form a masshaving water therein and an upper boundary, and having a pressurizedspace thereabove within the vessel; periodically opening the vessel froma point below the mass such that aliquots of liquid water or steam areforced from the mass while the vessel remains pressurized; andthereafter depressurizing the vessel and unloading the processed solidwaste therefrom.

Apparatus with Water Exhaustion Valves

The invention also includes an apparatus for processing solid wasteproducts, the apparatus comprising a rotatably mounted cylindricalvessel adapted to contain a waste product mass having an upper boundary,and having a first end, a second end and an interior surface, at leastone end terminating in a hatch that may be opened to allow access to theinterior of the vessel and sealably closed to allow pressurization ofthe vessel; a steam inlet for injecting steam into at least one of theends; and at least one valve disposed at a position so as be adapted toexhaust water or steam from a point below the upper boundary. It may bedesirable to provide the vessel with a plurality of valves disposedabout its outer cylindrical circumference. Optionally, the valve(s) maybe connected to a pump or similar equipment adapted to draw fluid fromthe vessel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an apparatus for processing solid wasteproducts in accordance with one embodiment of the present invention.

FIG. 1 a is another perspective view of an apparatus shown in FIG. 1.

FIG. 2 is a cross section view of the vessel for processing solid wasteproducts in accordance with one embodiment of the present invention.

FIG. 3 is another perspective view of an apparatus for processing solidwaste products in accordance with one embodiment of the presentinvention.

FIG. 4 is a plan view of an apparatus for processing solid wasteproducts in accordance with one embodiment of the present invention.

FIG. 5 is a cross section view of the vessel for processing solid wasteproducts in accordance with one embodiment of the present invention.

FIG. 6 is a schematic of a waste processing system with which thepresent invention may be used, for processing solid waste products inaccordance with one embodiment of the present invention.

FIG. 7 is a schematic of a waste processing system with which thepresent invention may be used, for processing solid waste products inaccordance with another embodiment of the present invention.

FIG. 8 is a longitudinal view of the cylindrical portion of a treatmentvessel, and shows an alternative embodiment of the present inventionwherein a plurality of straight blades are used in the vessel.

FIG. 9 is an elevation view of the cylindrical portion of a treatmentvessel, and shows an alternative embodiment of the present inventionwherein a plurality of straight blades are used in the vessel.

FIG. 10 is a perspective view of the cylindrical portion of a treatmentvessel, and shows an alternative embodiment of the present inventionwherein a plurality of straight blades are used in the vessel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In accordance with the foregoing summary, the following provides adetailed description of the preferred embodiment, which is presentlyconsidered to be the best mode thereof.

The invention relates to a process for recycling waste. This process issterilizing high density materials such as glass, plastics, metals andrecovering others from municipal solid waste (MSW) and converting paper,cardboard, food waste, etc. to a usable fiber and separating it fromother recyclable materials.

FIG. 1 shows an example of an apparatus for processing solid wasteproducts in accordance with one embodiment of the present invention.

FIG. 1 shows a rotatably mounted cylindrical vessel 1 having a firstend, a second end and an interior surface, at least one end terminatingin a hatch 2 that may be opened to allow access to the interior of thevessel and sealed closed to allow pressurization of the vessel. It ispreferred that the vessel have a hatch on either end such that thevessel may be opened to allow access to the interior of the vessel andsealed closed to allow pressurization of the vessel the charge of wasteproducts, and so that it may be loaded one end and removed at the otherend. This may be done, for example, by using a ram that may push thetreated charge from the vessel by extending through the vessel.

Also shown in FIG. 1 is a steam inlet 3 for injecting stem disposed atleast one of the ends, and preferably at both ends. Steam inlet 3 may beconnected to steam conduits (not shown) so as to introduce and maintainsteam pressure into the vessel.

The vessel may be rotated with respect to upper frame portion 5, such asby virtue of mechanical sleeve drives 6. The apparatus also includes atleast one motor or other means for rotating the vessel.

The motor(s) 7 may otherwise be connected to the vessel throughappropriate drive/transmission means, such as to sprocket by a chain orbelt.

Typically, the motor and drive means will be mounted in such anarrangement so as to move along with the movement of the vessel itself,such as by being mounted on a moveable frame 5 supporting the vessel.

Upper frame portion 5 in turn is supported by lower frame portion 8 thatincludes fulcrum pivot portion 9. Also shown in FIG. 1 are themechanical screw actuators 10 on either side of fulcrum pivot portion 9that move the vessel 1 between a position wherein the first end ishigher than the second end and a position wherein the second end ishigher than the first end. This movement allows the operator to balancethe load of the charge of waste products both before and during thesteam treatment and to agitate the charge longitudinally. Longitudinalagitation provides the ability to distribute cold spots that may developin the waste charge mass, thus providing a more uniform heating of thecharge. The actuators 10 may be linked in tandem across frame 8 by driverods 11 that are driven be respective electric motors 12.

The actuators 10 may include load sensors to determine the state ofbalance of the charge of waste products as originally loaded. Should thecharge of waste products be determined to be out of balance upon initialloading, the actuators 10 may be used to redistribute the load to evenits balance, either through back-and-forth oscillation or through rapidagitation, to cause the charge of waste products to shift in positionwithin the vessel. The load sensors may provide signals or informationto a microprocessor or PLC controller that is provided with programminginstructions to access the load at each sensor, and to provide feedbackinstructions to the actuators.

FIG. 1 also shows rotatably mounted cylindrical vessel 1 with the firstend raised with respect to the second end, such as would be the positionfor loading the vessel with the aid of input conveyor 13. This positionmay also be used to discharge the waste products after treatment ontodischarge conveyor 14, or to urge the charge of waste products towardthe second end in order to level the load of waste products duringprocessing. The position of vessel 1 may of course be varied along therange of positions from horizontal to any angle between the maximum tiltangle shown in FIG. 1, and its corresponding opposite.

FIG. 1 a is another perspective view of an apparatus shown in FIG. 1,showing the discharge or second end lower than the input or first end.

FIG. 3 shows, using the same reference numbers shown in FIG. 1, arotatably mounted cylindrical vessel 1 as depicted in FIG. 1 with thefirst end and the second end at about the same height such that thevessel is horizontal. This position is typical of those at which thevessel would be maintained during operation, with relatively smalladjustments being made to urge the charge of waste products towardeither end in order to level the load of waste products. This view alsoshows the second hatch 2 a (having steam inlet 3 a) which is used as anexit hatch for the treated waste product charge.

Conversely, FIG. 4 shows a top plan view of the rotatably mountedcylindrical vessel 1 as depicted in FIG. 1 with the second end raisedwith respect to the first end, such as may be necessary to move thecharge of waste products toward the first end in order to level the loadof waste products.

FIG. 5 is a longitudinal cross section view of the vessel system forprocessing solid waste products in accordance with one embodiment of thepresent invention, using the same lead lines from the FIGS. 1 and 2 andtaken along line 5-5 of FIG. 4. FIG. 5 shows the angling of one of theblades such as 16 a-16 d) shown in FIG. 2 (a cross-section along line2-2 of FIG. 4), and also shows that neighboring pairs of blades convergealternately toward opposite ends of the vessel. This view also showsthat the vessel may additionally comprise frusto-conical sections ateither end to assist in loading and unloading the vessel, and to helpmaintain portions of the charge of waste products oriented in theportion of the vessel provided with the blades for agitation. FIGS. 2and 5 also show that the blades are preferably slightly twisted suchthat ends of adjacent blades that converge are twisted away from oneanother while ends of adjacent blades that diverge are twisted towardfrom one another.

FIGS. 8, 9 and 10 show views of the cylindrical portion of a treatmentvessel as described herein, and shows an alternative embodiment of thepresent invention wherein a plurality of straight blades are used in thevessel.

FIG. 8 shows a longitudinal view of the cylindrical portion of atreatment vessel 20 in place of vessel 1 as described herein, wherein aplurality of straight blades 21 is used in the vessel. The blades 21 aremounted on individual mounting brackets 22 that serve to hold the blades21 away from interior surface 23. FIG. 8 is a view taken from line 8-8of FIG. 9. The mounting brackets 22 may also be used to mount thetwisted blades as described herein.

FIG. 9 is an elevation view of the cylindrical portion of a treatmentvessel 20, and shows in phantom a plurality of straight blades 21 andmounting brackets 22 holding the blades 21 away from interior surface23. FIG. 9 also shows a plurality of substantially straight blades 21protruding from the interior surface of the vessel, and each bladeextending substantially the entire length of the vessel, so as to becapable of transporting waste material from the bottom of the vesseltoward the top of the vessel, and releasing the waste material to fallto the bottom of the vessel.

FIG. 10 is a perspective view of the cylindrical portion of a treatmentvessel 20, and shows in phantom a plurality of straight blades 21 andmounting brackets 22 holding the blades 21 away from interior surface23.

FIG. 6 is a schematic of a waste processing system with which thepresent invention may be used, for processing solid waste products inaccordance with one embodiment of the present invention that permitsone-way steam flow through the vessel. This figure shows the variouscomponents of a system designed to provide the vessel with steam, andthe ancillary components of the preferred embodiment. This figure alsoshows the positions of valves and gauges using standard indicia, such ascontrol valves, check valves, thermocouples, strainers, pressure gauges,motors and pumps.

FIG. 7 is a schematic of a waste processing system with which thepresent invention may be used, for processing solid waste products inaccordance with another embodiment of the present invention that permitstwo-way steam flow through the vessel that may be provided in pulses.This figure also shows the positions of valves and gauges using standardindicia, such as control valves, check valves, thermocouples, strainers,pressure gauges, motors and pumps. This schematic provides an example ofa system that permits steam, particularly superheated steam, to beprovided in pulses to the vessel of the present invention.

The views of FIGS. 3 and 4 are used for illustrative purposes only, andit will be understood that the vessel may be titled to lesser degreesduring processing in order to make lesser adjustments in the loaddistribution through leveling, and that such movement may be relativelyrapid or slower and/or repetitive, depending upon the load situationpresented.

FIG. 2 also shows an example of a line 17 representing the top of awaste product charge as it would appear once leveled within the vessel1. The waste product charge leaves a zone of space 18 above it such thata steam region extends the length of the vessel through which successiveportions of the waste products will pass as the vessel rotates. It ispreferred that the interior of the vessel be substantially free ofstructure presenting surfaces that are not substantially parallel to thecentral longitudinal axis of the vessel.

The operation of the vessel can be appreciated from the cross-section ofthe apparatus shown in FIG. 2 showing vessel 1, interior surface 15 andblades 16 a-16 d.

The blades may be straight and substantially parallel to thelongitudinal axis of the vessel, or, as shown in FIG. 2, preferably maybe angled such that neighboring blade pairs (e.g., 16 a and 16 b)converge toward one end of the vessel, while successive blade pairs(e.g., 16 b and 16 c) converge toward the opposite end of the vessel, asseen in FIG. 2. The straight blades permit portions of the waste chargeto be raised vertically and dropped vertically as the vessel rotates.The angled blades as described above further cause an alternatingside-to-side movement of successive portions of the waste charge, as thevessel rotates, by allowing successive portions of the waste charge tofall at an angle to the vertical such that the successive portions aremoved gently from side to side without compaction.

After the vessel is loaded with the charge of waste products, the doorthrough which the charge was loaded is shut, steam is introducedcontinually into the vessel, and the vessel becomes pressurized. Freshsteam may be continuously fed into the vessel from the loading end, andafter a predetermined processing pressure is reached, steam may beallowed to escape the vessel into the discharge steam line.

The temperature and pressure of the vessel are monitored, and the flowof steam is regulated to keep the process within predeterminedprocessing ranges (typically around 70-100 psi, at 300-335° F.). Thevessel is rotated at a predetermined speed (depending on the size of thevessel), and after a requisite time and temperature profile is achievedamount of time (typically 20 to 45 minutes), the pressure is releasedand the processed waste is removed.

The temperature of the charge of waste products may be monitored bythermometers or thermocouples disposed along the length of the vessel.The temperature readings are taken and applied to determine thetemperature of portions of the charge of waste products. Thethermometers or thermocouples may provide signals or information to amicroprocessor or PLC controller that is provided with programminginstructions to access the temperature at each thermometers orthermocouples, and to provide feedback instructions to the actuators.This information may be used as feedback control to the actuators 9 inorder to adjust the charge of waste products within the vessel so as toincrease heat transfer to portions of the charge not receiving effectiveheat treatment, in order to maintain overall efficient heat transfer tothe charge of waste products overall.

A given charge of waste products may contain a wide variety ofconstituents, such as wood, paper, organic matter, water, etc. Eachcharge of waste products presents its own heat capacity and transferprofile, while there is required an overall heat absorption of the massin order to provide an effective treatment of the waste products charge.

The information from the thermometers or thermocouples may also be usedto determine the heat absorption over time as the charge of wasteproducts heats up initially. This allows the operator (or amicroprocessor or PLC controller) to extrapolate the energy needs forthat charge of waste products and, based upon a comparison of the heattransfer profile, to also determine the approximate qualitativeconstituent make-up of the charge of waste products, and thus allow thedetermination of the treatment time necessary to treat that particularcharge.

In operating the vessel of the present invention, the vessel may betilted so as to present the input hatch 2 upward with respect to thehorizontal, and to allow a charge of waste products to be placed intothe vessel with the aid of conveyor 13. The hatch 2 is then closed andthe waste products 17 charge (see FIG. 2) may optionally be leveled by areciprocating action of the actuators 10 prior to introduction of steam,or upon initial introduction of steam.

Once the hatch 2 is sealed, steam is placed into the vessel throughinlets 3 and/or 3 a to provide a pressurized steam environment in thevessel 1. Examples of systems used to produce and inject the steam areshown in FIGS. 6 and 7.

The vessel 1 is then rotated and the blades 16 a-16 d (or blades 21 inFIGS. 8-10) act to raise portions of the waste products charge 17 fromthe bottom to the top of the vessel, and then release them to fallthrough the a zone of the steam environment 18 of relatively low density(i.e., that space not occupied by the waste products 17 as seen in FIG.2. This zone increases in volume as the waste products 17 shrinks duringthe processing.

The cylindrically shaped vessel 1 has a number of blades to function asa stirring apparatus to homogenize heat and circulate the wastevertically and/or horizontally, and at least one opening to load anddischarge waste (i.e., hatches 2 and 2 a, respectively). The conicalstructures at the openings enhance the input of the waste productscharge and the discharge of the treated waste. These structures alsoserve to maintain the waste in the central horizontal region of thevessel. The vessel may be titled by its longitudinal axis with respectto the horizontal position for effective waste loading into the vesselby the gravity force. This tilting may also be used during theprocessing to level the waste products charge.

According to the invention, steam inlets are connected to one or moresaturated or superheated steam supply and to a steam receiver. In thisway, the vessel is pressurized and depressurized from one or moreopenings. Each opening may be provided with a pressure lock andbidirectional steam flow conduits and valves. The apparatus may alsoinclude an optional steam vacuum pump at each opening for rapiddepressurizing of the vessel. Rotating union valves may also be includedto enable steam flow in-out of the vessel as the vessel is rotating ortilting. These features are shown schematically in FIGS. 6 and 7.

Load cells that are attached to or independent of the actuator(s) andconnected to the frame structure detect when the process material withinthe vessel is non-uniformly distributed along the vessel's horizontalaxis. Uniform distribution of waste in the vessel is attained byrotating the vessel on its latitude axis in accordance with and by thereference to load cell signals.

As the vessel rotates, the temperature is monitored to determine thechange in temperature of the waste products charge over time. Aplurality of temperature sensors may be used to send feedback to thecontrol to achieve homogenous temperature in the vessel. The feedbackcontrol system and controller may include PLC or microprocessors thataccept data from the temperature and load sensors and provide feedbackcontrol to the vessel rotation and the actuators to reposition andredistribute the waste charge load as required for efficient processing.

It is preferred that the heated and pressurized vessel is rotatedbidirectionally, and at a constant or variable speed depending on thewaste type, to attain homogenous heat transfer during the treatmentcycle. As the waste shrinks due to the pressure and temperature, thevolume of the waste charge decreases. The open space, such as the volumeof space 18, increases by shrinkage in the vessel and serves as a hotregion to provide heat treatment to portions of the waste charge thatare raised and allowed to fall through this relatively low densityregion. This provides most complete and efficient exposure of the wasteto the steam environment.

This temperature data may also be used to determine the overallabsorption of energy over time which in turn allows the operator tocharacterize the waste products qualitatively (e.g., in terms of overallmakeup of organic matter, paper, etc.) through pre-determined data onwaste product constituents, and thereby to extrapolate the amount oftime a given charge of waste products will require to completeprocessing. This information may be stored and fed back into the controlsystem to determine a time when the processing may be stoppedautomatically or through a signal to the operator.

As a result of steam condensation during this process, sludge maydevelop, and to avoid mixing the recycled waste with the sludge, one ormore gaps or perforations may be provided in the blades (preferably nearthe interface between the blades 16 a-16 d and the interior surface 15;see e.g. blades 16 b and 16 d having perforations and gaps,respectively) to allow the sludge to remain at the bottom of the vesseland the stirring mechanism and the chamber keeps the sludge at thebottom of the vessel. This may also be done by using the mountingarrangement shown in FIGS. 8-10. The perforations shown in FIG. 2 mayalso be used in the straight blades shown in FIGS. 8-10, and themounting arrangement shown in FIGS. 8-10 may also be used with the bladetype and arrangement shown in FIG. 2.

Due to the fact that the amount of sludge would vary depending on thesteam type and quality, superheated, dry steam, may be used in place ofconventional saturated steam to reduce the amount of sludge.

Also, during rotation of the vessel, the thermocouples determine whetherthe waste products charge has developed relatively cold regions, such asthrough the make up of the charge itself, or through compaction, that isretarding the rate of heat transfer to that region. If a relatively coldregion is detected, the vessel may be tilted and/or oscillated by theactuators to redistribute the mass along the length of the vessel. Also,in the event the waste products charge otherwise becomes unbalanced, theactuators may tilt and/or oscillate the vessel to redistribute the massalong the length of the vessel. This may be done through PLC controllersor microprocessors operating in conjunction with the thermocouples andactuators.

Through the action of the actuators, the waste charge can be maintainedrelatively evenly distributed along the length of the vessel duringprocessing, so that the blades are able to raise portions of the wasteproducts charge that are substantially uniformly distributed along thelength of the vessel, and to allow those portions to descend through arelatively low density zone created and maintained along the length ofthe treatment volume of the vessel.

The tilting pivot point is preferably located at the center of gravityto balance the weight at horizontal position and to incline the vesselat an adjustable bidirectional angle relative to its horizontalposition. Mechanical linear actuators, chain systems, hydraulicactuators, pinion rack systems, and scissors systems, etc. are types ofmechanisms that may be used in providing the tilting movement.

This system therefore prevents and dynamically rectifies unbalancedloads and any other sources of localized compaction of the wasteproducts charge, and allows efficient treatment of the waste productscharge by creating and maintaining a low density zone through whichindividual portions of the waste products charge are passed withincreased efficiency and without compaction of portions of the wasteproducts charge as occurs in other treatment vessel systems with activetransport systems or vessels that permit portions of the waste productscharge to remain compressed or in a state of non-uniform distribution.

Another aspect of the present invention relates to water exhaustionduring processing. An example of the method and apparatus of this aspectof the present invention may be appreciated by reference to FIGS. 2 and3. These Figures show one or more optional valves placed so that theymay be opened to exhaust water, typically in the form of a mixture ofwater and steam, to be exhausted from below the waste mass beingprocessed. As may be appreciated from FIG. 2, when the valve 26 isopened while the vessel is pressurized, the pressure of the steam inregion 18 causes any water collected at the bottom of the vessel 1 (andprogressively any interstitial water in the mass 17), to be exhausted(at these operating pressures in the form of steam). This exhaustion isthen preferably followed by repeated cycles for pressurizing the vesseland further processing the waste mass, followed by further waterexhaustion cycles. This process leads to a dryer processed mass uponcompletion of the time/temperature process cycle that is necessary toeffectively render the waste mass to the physical and chemicalcharacteristics desired.

FIG. 3 shows valves 25 and 26. These valves may be of any typeappropriate for the function. Preferably, they may be fitted with means,such as screens that allow water and steam to be exhausted as describedherein while preventing fouling of the valve opening. The water may beevacuated to atmospheric pressure, or may even be evacuated under theinfluence of vacuum such as through the use of vacuum pump 27 attachedto valve 25 as shown in FIG. 3.

The valves may also be placed in a series around the vessel such thatthe vessel may be halted at any point such that a valve is positioned ator near the bottom of the vessel, or otherwise at a point below theupper boundary of the waste mass within the vessel. An example of suchas arrangement is shown in the position of the valves 28 and 29 in FIG.8, although more valves may be added to form a series about thecircumference of the vessel.

It is apparent that while specific embodiments of the invention aredisclosed, various modifications of the apparatus or parameters of theprocess may be made which will be within the spirit and scope of theinvention. Therefore the spirit and scope of the present inventionshould be determined by reference to the claims below.

What is claimed is:
 1. A method of processing solid waste products in avessel, said vessel including a valve, said method comprising: loadingthe vessel with a charge of solid waste products along the bottom ofsaid vessel; sealing the vessel; introducing steam into said vessel soas to pressurize said vessel; rotating said vessel so as to cause saidcharge of solid waste products to be moved from the bottom of saidvessel to toward the top of said vessel, whereby some of said steamcontacts said solid waste products and condenses as liquid water withinsaid vessel; periodically halting the rotation of said vessel such thatsaid solid waste products settle to the bottom of said vessel and saidliquid water forms a water line within said vessel and such that saidvalve is disposed below said water line, and opening said valve from theoutside of said vessel and removing aliquots of said liquid water fromsaid vessel while said vessel is pressurized; and thereafterdepressurizing the vessel and unloading the processed solid wastetherefrom.
 2. A method according to claim 1 wherein said liquid water isdrawn from said vessel by a pump adapted to draw said liquid water fromsaid vessel.
 3. A method according to claim 1 wherein said water isremoved from a point below said charge of solid waste products such thataliquots of liquid water are forced from said charge of solid wasteproducts while said vessel remains pressurized during said removal ofsaid aliquots of water.
 4. A method according to claim 1 wherein saidvessel is maintained at a temperature of from about 300 degrees to about335 degrees Fahrenheit.
 5. A method according to claim 1 wherein thepressure with said vessel is maintained in the range for from about 70to about 110 psia.
 6. A method according to claim 1 wherein water isbound in said charge of solid waste products, and wherein the pressurewith said vessel is cycled between a lower pressure by the exhaustion ofsteam to cause the evaporation of said bound water, and a higherpressure by the introduction of steam.
 7. A method according to claim 6wherein said lower pressure is in a range of from about 5 psia to about15 psia.
 8. A method according to claim 1 wherein water is bound in saidcharge of solid waste products, and wherein, after removal of an aliquotof liquid water, the pressure with said vessel is cycled between a lowerpressure by the exhaustion of steam to cause the evaporation andexpansion of said bound water, and a higher pressure by the introductionof steam.
 9. A method according to claim 8 wherein said lower pressureis in a range of from about 5 psia to about 15 psia.
 10. A methodaccording to claim 1 wherein said aliquots of liquid water are recycledto create steam which is reintroduced into said vessel.
 11. A methodaccording to claim 1 wherein said steam is superheated steam introducedin pulses into said vessel.
 12. A method according to claim 1 whereinsaid vessel comprises a valve disposed on one side of the center axisthereof and wherein said one side of said vessel is positioned lowerthan the opposite side prior to the removal of an aliquot of liquidwater from said vessel.